606 The Animal Kingdom 



a rather vicious disposition. It is carnivorous in its habits and has a 

 bad reputation for its capture and devouring of duckhngs. Its flesh is 

 highly valued for eating purposes. Both Pseitdemys and Chrysem.ys are 

 brightly colored species which are frequently seen sunning themselves 

 on logs in ponds. The soft-shelled turtle, Amyda (Fig. 202,w) as its 

 name implies has a soft, leathery shell. It has become thoroughly aqua- 

 tic and carnivorous in its habits ; it goes to land to lay its eggs. The 

 gopher turtle, Gopherus, often is very abundant in the southern states. 

 It makes extensive excavations and prefers regions which are quite dry 

 and sandy. It is vegetarian in its eating habits. A close relative 

 of Gopherus, Testudo, is found on the Galapagos Islands and on some 

 islands of the Indian Ocean. These latter are giant land turtles which 

 may exceed over 4 feet in length and weigh over 300 pounds. 



Probably of greatest economic importance are the sea turtles of 

 the family Chelonidae. These turtles have the legs modified as flippers 

 and are thoroughly aquatic in their habits. They spend nearly their 

 entire life at sea, returning to land only to lay their eggs. Both the flesh 

 and eggs are valued as food. The shell of the members of the genus 

 Caretta is highly valued as a source of tortoise shell. 



The largest of the living turtles are the members of the genus 

 Dermochelys, the leatherbacks, which may weigh over 1,000 pounds. 

 They are members of another family of sea turtles. 



The terms turtle, tortoise, and terrapin are loosely used and have 

 no real significance. In general, the terrestrial species are called "tor- 

 toises," the aquatic ones, "turtles," and some few hard-shelled, edible 

 aquatic forms, "terrapins." 



The Order Squaniata (the Lizards and Snakes). — In contrast 

 to the deliberate, slow-moving turtles, the members of this order are 

 usually fast moving forms. While the turtles have relied upon armor 

 for protection, the members of this order rely more upon speed and 

 behavior for escaping from their enemies. This order is divided into 

 two suborders : the Sauria which includes the lizards, and the Ser- 

 pentes which includes the snakes. Superficially it would seem simple 

 to separate these two groups on the basis of the presence or absence of 

 legs ; however, there are lizards without legs. The only real differences 

 between the members of the two suborders are based upon internal 

 skeletal structures. The snakes lack a pectoral girdle, have the two 

 halves of the lower jaw joined by a ligament, and the brain case is 

 closed anteriorly. In addition they have no movable eyelids, no func- 



